mash the blueberries and place in a heavy pot. add the sugar, salt and key lime juice. bring to a boil, reduce heat and let simmer about 5 minutes. increase heat and bring to a boil. stir in the pectin and boil for a full 60 seconds. turn off heat and place in sterilized jars. process for long term storage as necessary. *this is a small batch, so you may choose to keep in a jar in the fridge for your daily use. it is also delicious in my homemade pop-tarts